11 Aug
2010
11 Aug
'10
10:57 a.m.
Tony Duell wrote:
It depends on what you wnat to use that serial portr for. IIRC the s7201
has various synchronous modes that can be very useful
Nice machine. The QX10 is one of my favourite
desktop CP/M machines. The
video system is based round a 7220, the serial port (IIRC) uses a 7201.
Using a uPD7201 for the serial port is a strike against it. High speed
modems that transport asynchronous data over a
synchronous modulation,
such as V.22, V.22bis, V.32, etc., have to use V.14 procedures to handle
cases where the transmitting device is overspeed relative to the
modulation, or the transmitting modem is overspeed relative to the
receiving side. In the former case, up to one out of ten stop bits get
dropped over the modulation, and reinserted on the receiving side. When
that happens, or in the case that the transmitting system's modulation
is faster than the receiving side (due to crystal tolerances, etc.), the
receiving side is allowed to shave off a portion of each stop bit on the
serial interface.
Right,,, Now that I did not know. However, I would not think a QX10 was a
natural machine to connect such a modem to,
-tony